Additive-free normal temperature yogurt and preparation method therefor

Abstract

An additive-free normal temperature yogurt and a preparation method therefor. A slime-producing bacterium is used as a fermentation strain, and same is used in combination with a stabilizer, such as citrus fiber, seaweed powder and glutinous rice starch. The preparation method for the additive-free normal temperature yogurt comprises: adding white granulated sugar, citrus fiber, seaweed powder and glutinous rice starch into milk at 18°C-25°C for material dissolution, performing homogenization and sterilization after the material dissolution to obtain a mixed material liquid, inoculating and fermenting the mixed material liquid to obtain fermented milk, and performing pasteurization on the fermented milk to obtain the normal temperature yogurt, wherein the citrus fiber is citrus fiber after performing freezing and grinding.

Description

Zero-additive room-temperature yogurt and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of dairy products, and in particular provides a zero-additive room-temperature yogurt and a preparation method thereof. Background Art

[0002] There are countless types of yogurt on the market, and most require food additives to maintain the stability of the yogurt system. Depending on the source of food additives, they can be divided into two categories: natural yogurt stabilizers and synthetic yogurt stabilizers. For zero-additive yogurt, natural yogurt stabilizers are preferred.

[0003] Natural yogurt stabilizers, due to their inherent properties and flavor, often affect the flavor and mouthfeel of zero-additive yogurt. Furthermore, it's difficult to guarantee the long-term stability of zero-additive, ambient-temperature yogurt throughout its shelf life. Therefore, research on natural yogurt stabilizers focuses on optimizing their formulation and addition methods.

[0004] Natural yogurt stabilizers, such as citrus fiber, are a dietary fiber extracted from citrus peels that swells upon absorbing water. When combined with water, citrus fiber forms a viscous substance, increasing the viscosity of the yogurt. Because citrus fiber and other natural yogurt stabilizers can serve as fermentation substrates for starter cultures, the role of natural yogurt stabilizers over the shelf life of ambient temperature yogurt as storage increases is unclear.

[0005] Summary of the Invention

[0006] The existing technology adds citrus fiber, seaweed powder, and physical starch to yogurt systems, primarily to achieve a stable, non-watering yogurt during its shelf life. However, the addition of citrus fiber significantly increases the viscosity of the yogurt over time, severely impacting its taste and stability.

[0007] In order to overcome the defects of the prior art, the present invention provides a zero-additive room-temperature yogurt and a preparation method thereof.

[0008] In a first aspect, the zero-additive room-temperature yogurt provided by the present invention uses slime-producing mold as the fermentation strain, and the addition amount of the fermentation strain is 200 dcu / ton; the stabilizer of the zero-additive room-temperature yogurt includes: citrus fiber, seaweed powder and glutinous rice starch, and the citrus fiber is citrus fiber after freeze-grinding. The conditions of the freeze-grinding are: soaking the coarsely ground citrus fiber in liquid nitrogen for 3-5 minutes, forming a layer of ice on its surface, and then grinding it until the fineness is 150-220 mesh.

[0009] This invention employs a novel approach to address the issue of viscosity rebound during the shelf life of ambient temperature yogurt products stabilized with citrus fiber, seaweed powder, and glutinous rice starch. Specifically, the invention utilizes significantly improved citrus fiber as a raw material, combining this improved citrus fiber with seaweed powder and glutinous rice starch to significantly improve the viscosity rebound of ambient temperature yogurt during its shelf life.

[0010] This method freeze-grinds citrus fiber, significantly increasing its fineness and yielding significantly improved fluidity, dispersibility, and hydration properties, which can be used as a stabilizer in yogurt preparation. Compared with other grinding methods, citrus fiber obtained through liquid nitrogen freeze-grinding significantly improves the stickiness of yogurt caused by citrus fiber, while also maintaining the shelf life and improving the taste of ambient temperature yogurt.

[0011] As a zero-additive room-temperature yogurt, the raw materials used in the present invention are only composed of milk, frozen and ground citrus fiber, seaweed powder, glutinous rice starch, white sugar and slime-producing fungi.

[0012] Specifically, in the zero-additive room-temperature yogurt provided by the present invention, the ratio of frozen-ground citrus fiber, seaweed powder, and glutinous rice starch is (1-4):(2-6):(14-20) by mass.

[0013] More specifically, the ratio of the frozen ground citrus fiber, seaweed powder and glutinous rice starch is 1:2:14 or 4:6:20 by mass.

[0014] The zero-additive room-temperature yogurt provided by the present invention comprises 871-903 parts by weight of milk, 1-4 parts by weight of frozen and ground citrus fiber, 2-6 parts by weight of seaweed powder, 12-20 parts by weight of glutinous rice starch and 70-90 parts by weight of white granulated sugar.

[0015] In a second aspect, the present invention provides a method for preparing the above-mentioned zero-additive room-temperature yogurt, comprising: adding white sugar, frozen-ground citrus fiber, seaweed powder, and glutinous rice starch to pretreated milk in sequence to obtain a mixed liquid, and fermenting the mixed liquid using slime-producing fungi to obtain the zero-additive room-temperature yogurt.

[0016] The pretreatment is to heat the milk to 55-60° C. to facilitate mixing of the materials.

[0017] The present invention is based on the combination of specific citrus fiber, seaweed powder and glutinous rice starch, which effectively simplifies the preparation method, and the yogurt stabilizer with natural ingredients and white sugar can be mixed at one time.

[0018] More specifically, the method for preparing the zero-additive room-temperature yogurt of the present invention comprises:

[0019] (1) heating the milk to 55-60° C., sequentially adding white sugar, frozen ground citrus fiber, seaweed powder, and glutinous rice starch to the heated milk, and then homogenizing and sterilizing to obtain a mixed liquid;

[0020] (2) cooling the mixed liquid of step (1) to 40-42° C., adding Lactobacillus bulgaricus and Streptococcus thermophilus to ferment until the pH value reaches 4-4.3, breaking the emulsion, stirring and cooling to obtain fermented milk;

[0021] (3) pasteurizing and cooling the fermented milk obtained in step (2) to obtain the zero-additive room-temperature yogurt.

[0022] In the preparation method provided by the present invention, the homogenization conditions in step (1) are: primary pressure 110-150 bar, secondary pressure 50-80 bar; the sterilization conditions in step (1) are: 130-135° C., 3-5 s.

[0023] In the preparation method provided by the present invention, the speed of the demulsification stirring in step (2) is 35-40 revolutions per minute, and the stirring is performed for 10-12 minutes.

[0024] As a specific embodiment of the present invention, a method for preparing zero-additive room temperature yogurt comprises:

[0025] (1) After the milk is transferred from the milk silo, it is directly pumped into the hot plate at a pressure of 10-15 bar to heat the milk to 45-60°C in a cycle. After the temperature is raised, the milk is directly pumped into the mixing tank and the raw materials are added. During the process of adding the raw materials, the milk is not heated in a cycle, which reduces the shearing of the product stabilizer and improves the product stability.

[0026] The raw materials added are white sugar, citrus fiber, seaweed powder and glutinous rice starch in sequence. After the feeding is completed, the product is homogenized and the homogenization pressure is: the first-level pressure is 110-150 bar, and the second-level pressure is 50-80 bar. After homogenization is completed, it is sterilized at a sterilization temperature of 130-135 ° C and a sterilization time of 3-5 seconds to obtain a mixed liquid.

[0027] (2) The mixed liquid is cooled to 40° C., Lactobacillus bulgaricus and Streptococcus thermophilus are added, and fermented in a fermenter. When the pH value reaches 4-4.3, the emulsion is broken and stirred at a stirring speed of 35-40 rpm for 10-12 minutes. After stirring, it is quickly cooled in the fermenter to 20-25° C. to obtain cooled fermented milk.

[0028] (3) The cooled fermented milk is pasteurized at 95°C for 200-300 seconds and cooled to 20-25°C to obtain zero-additive room temperature yogurt.

[0029] In addition, the inventors found that the problem of citrus fiber and seaweed powder sticking to the tube still existed during the ultra-high temperature instantaneous sterilization stage. To solve this problem, the present invention further provides the following technical solutions.

[0030] In one aspect, the present invention provides a method for preparing room-temperature yogurt, comprising: adding white sugar, citrus fiber, seaweed powder, and glutinous rice starch to milk at 18 to 25° C. for blending, homogenizing and sterilizing the blended materials to obtain a mixed liquid, inoculating and fermenting the mixed liquid to obtain fermented milk, and pasteurizing the mixed liquid to obtain the room-temperature yogurt;

[0031] The citrus fiber is frozen ground citrus fiber, and the processing method is as described above.

[0032] As mentioned above, freezing and grinding citrus fiber can improve the back-adhesion defect of yogurt caused by citrus fiber during the shelf life, but in industrial production, there is a problem of citrus fiber and seaweed powder sticking to the tube during the ultra-high temperature instantaneous sterilization stage. This may be caused by the back-adhesion characteristics of natural raw materials such as citrus fiber. Therefore, faced with this problem, the inventor first thought of replacing citrus fiber or further modifying citrus fiber, but after a series of attempts, did not obtain the desired effect. However, it was unexpectedly discovered during the research process that in the chemical stage, the use of low-temperature (18-25°C) chemical materials, rather than the 55-60°C chemical materials as described above, can effectively solve the problem of citrus fiber and seaweed powder sticking to the tube during the ultra-high temperature instantaneous sterilization stage, and has no obvious negative impact on the stability and taste of the final product.

[0033] Here, the fermentation bacteria are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus (ie, Lactobacillus bulgaricus and Streptococcus thermophilus), and the addition amount of the fermentation bacteria is 200 dcu / ton.

[0034] Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus are slime-producing fungi. Using them in fermentation substrates containing specific citrus fiber, seaweed powder and glutinous rice starch is conducive to achieving good fermentation effects and product stability.

[0035] In some embodiments of the present invention, the mass ratio of citrus fiber, seaweed powder and glutinous rice starch after freeze-grinding is (1-4):(2-6):(10-20).

[0036] Controlling the ratio of frozen ground citrus fiber, seaweed powder, and glutinous rice starch within the aforementioned range helps improve yogurt stickiness while maintaining the stability and taste of the yogurt throughout its shelf life. Furthermore, the present inventors have found that using a cold-melted material can reduce the amount of glutinous rice starch used to a certain extent without significantly affecting the final result.

[0037] According to the preparation method of room temperature yogurt provided by the present invention, in addition to the fermentation bacteria, the raw materials of the room temperature yogurt are, in parts by weight, 880-917 parts of milk, 1-4 parts of frozen and ground citrus fiber, 2-6 parts of seaweed powder, 10-20 parts of glutinous rice starch and 70-90 parts of white sugar.

[0038] In some embodiments of the present invention, the method for preparing the room temperature yogurt comprises:

[0039] (1) heating the milk to 18-25° C., adding white sugar, citrus fiber, seaweed powder and glutinous rice starch, and sterilizing the mixture by homogenization to obtain a mixed liquid;

[0040] (2) After cooling the mixed liquid to 40-42° C., adding Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus to ferment until the pH value reaches 4-4.3, stirring and breaking the emulsion, and cooling to obtain fermented milk;

[0041] (3) pasteurizing the cooled fermented milk and cooling it to obtain the room temperature yogurt.

[0042] Furthermore, in step (1), the homogenization conditions are: primary pressure 110-150 bar, secondary pressure 50-80 bar; and the sterilization conditions are: 125-135° C., 3-5 s.

[0043] Furthermore, in step (2), the rotation speed of the demulsification stirring is 35-40 revolutions per minute, and the stirring time is 10-12 minutes.

[0044] Furthermore, in step (3), the pasteurization conditions are: 95° C., 200-300 s, optionally 300 s.

[0045] In a specific embodiment of the present invention, the method for preparing the room temperature yogurt comprises:

[0046] After milk is blended in the milk silo, it is heated to 20°C on a hot plate and then directly pumped into the batching tank. White sugar, citrus fiber (frozen ground citrus fiber), seaweed powder, and glutinous rice starch are added. After the ingredients are added, the product is homogenized at a primary pressure of 110 bar and a secondary pressure of 70 bar. After homogenization, it is sterilized at 130°C for 5 seconds. The liquid is cooled to 40-42°C before the bacteria (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus) are added. Fermentation occurs in a fermenter. When the pH reaches 4.3, the milk is demulsified and stirred at 35 rpm for 10 minutes. After stirring, the milk is rapidly cooled in the fermenter to 20°C, resulting in the fermented milk. The cooled fermented milk is then pasteurized at 95°C for 300 seconds. After cooling to 25°C, it is canned.

[0047] On the other hand, the present invention provides a room-temperature yogurt, which is prepared by the above-mentioned preparation method. The raw materials of the room-temperature yogurt are: 880-917 parts of milk, 1-4 parts of frozen and ground citrus fiber, 2-6 parts of seaweed powder, 10-20 parts of glutinous rice starch and 70-90 parts of white sugar, and fermentation strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus.

[0048] Furthermore, the raw materials of the room temperature yogurt are as follows: 888.1 to 917 parts of milk, 1 to 4 parts of frozen and ground citrus fiber, 2 to 6 parts of seaweed powder, 10 to 11.9 parts of glutinous rice starch, 70 to 90 parts of white sugar, and fermentation bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus.

[0049] The present invention not only provides a room-temperature yogurt without adding food additives and completely utilizing raw materials to build a stable product system, but also uses low-temperature materials so that the amount of glutinous rice starch in the product of the present invention can be reduced.

[0050] The room-temperature yogurt of the present invention does not separate out water when placed at 38° C. for 6 months.

[0051] Beneficial effects of the present invention:

[0052] The present invention provides ambient temperature yogurt without any food additives, utilizing raw materials to create a stable product system. Citrus fiber, obtained by pre-treating it with liquid nitrogen and freeze-grinding, is combined with seaweed powder and glutinous rice starch as stabilizers. This stabilizes the yogurt system while mitigating the sticking problem caused by citrus fiber during its shelf life.

[0053] The present invention uses fermentation bacteria Lactobacillus bulgaricus and Streptococcus thermophilus in a fermentation substrate containing specific citrus fiber, seaweed powder and glutinous rice starch, thereby achieving a good yogurt fermentation effect, simplifying the addition method of the yogurt stabilizer, and further simplifying the yogurt preparation method.

[0054] Furthermore, the present invention unexpectedly discovered that using a low-temperature refrigeration temperature of 18-25°C effectively solves the problem of citrus fiber and seaweed powder becoming sticky during ultra-high temperature instantaneous sterilization and pasteurization, without significantly negatively impacting the stability and taste of the final product. Furthermore, using refrigerated materials, the ambient temperature yogurt of the present invention can also reduce the amount of glutinous rice starch used, resulting in a cleaner formula. DETAILED DESCRIPTION

[0055] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0056] The term "include" or "comprising" in the present invention is an open description containing the specified components or steps described, as well as other specified components or steps that do not substantially affect them.

[0057] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0058] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0059] Example 1

[0060] This embodiment provides a formula and preparation method of zero-additive yogurt, as follows:

[0061] The recipe for zero-additive yogurt is:

[0062] 903 parts by weight of milk, 1 part by weight of frozen and ground citrus fiber, 2 parts by weight of seaweed powder, 14 parts by weight of glutinous rice starch and 80 parts by weight of white sugar; the added amount of fermentation bacteria is 200 dcu / ton.

[0063] The method of freeze grinding citrus fiber is liquid nitrogen treatment: soak the coarsely ground 60-mesh citrus fiber in liquid nitrogen for 3-5 minutes to form a layer of ice on its surface, and then continue to grind it to a fineness of 200 mesh.

[0064] The preparation method of zero-additive yogurt is as follows: (1) after milk is adjusted from the milk silo, the milk is directly beaten into the hot plate using a pressure of 10 bar to heat the milk to 55°C in a circulating manner, and then directly beaten into the mixing tank after the heating is completed; raw materials are added, and the milk is not circulated and heated during the addition of raw materials, thereby reducing the shear of the product stabilizer and improving the stability of the product.

[0065] The raw materials added are white sugar, citrus fiber, seaweed powder and glutinous rice starch. After the addition, the product is homogenized. The homogenization pressure is 110 bar at the first level and 70 bar at the second level.

[0066] After homogenization, sterilization is carried out at a temperature of 130°C and a sterilization time of 5 seconds.

[0067] (2) The feed liquid of step (1) was cooled to 40° C., Lactobacillus bulgaricus and Streptococcus thermophilus were added and fermented in a fermenter. When the pH value reached 4.3, the emulsion was broken and stirred at a stirring speed of 35 revolutions per minute for 10 minutes. After the stirring was completed, the mixture was quickly cooled in the fermenter to 20° C. to obtain cooled fermented milk.

[0068] (3) The cooled fermented milk was pasteurized at 95°C for 300 seconds and cooled to 25°C to obtain zero-additive room temperature yogurt.

[0069] Example 2

[0070] This embodiment provides a formula and preparation method of zero-additive yogurt, as follows:

[0071] The recipe for zero-additive yogurt is:

[0072] 888 parts by weight of milk, 4 parts by weight of frozen and ground citrus fiber, 6 parts by weight of seaweed powder, 20 parts by weight of glutinous rice starch and 82 parts by weight of white sugar; the added amount of fermentation bacteria is 200 dcu / ton.

[0073] The method of liquid nitrogen rapid freezing and grinding of citrus fiber is the same as that in Example 1, and the fineness of the citrus fiber used is 180 mesh.

[0074] The preparation method is as follows: (1) after the milk is adjusted from the milk silo, the milk is directly beaten into the hot plate (hot plate temperature) at a pressure of 15 bar to heat the milk to 60°C in a circulating manner. After the heating is completed, the milk is directly beaten into the mixing tank and the raw materials are added. During the process of adding the raw materials, the milk is not circulated and heated, so as to reduce the shear of the product stabilizer and thus improve the stability of the product.

[0075] The added raw materials are white sugar, citrus fiber, seaweed powder and glutinous rice starch in order. After the feeding is completed, the product is homogenized with a first-level homogenization pressure of 120 bar and a second-level pressure of 50 bar. After homogenization is completed, it is sterilized with a sterilization temperature of 130°C and a sterilization time of 5 seconds to obtain a mixed liquid.

[0076] (2) The mixed liquid was cooled to 40°C, and Lactobacillus bulgaricus and Streptococcus thermophilus were added to ferment in a fermenter. When the pH value reached 4.3, the emulsion was broken and stirred at a stirring speed of 35 rpm for 10 minutes. After stirring, the mixture was quickly cooled in the fermenter to 20°C to obtain cooled fermented milk.

[0077] (3) The cooled fermented milk was pasteurized at 95°C for 300 seconds and cooled to 25°C to obtain zero-additive room temperature yogurt.

[0078] Example 3

[0079] This embodiment provides a formula and preparation method of zero-additive room temperature yogurt, as follows:

[0080] The formula used in this example is the same as that in Example 2. The method of liquid nitrogen rapid freezing and grinding of the citrus fiber is the same as that in Example 1. The fineness of the citrus fiber used is 150 mesh, and the preparation method of the citrus fiber used is the same as that in Example 1.

[0081] Example 4

[0082] This embodiment is the same as embodiment 2, except that the fineness of the citrus fiber used is 220 mesh.

[0083] Example 5

[0084] This embodiment provides a room temperature yogurt, the formula of which is as follows:

[0085] 900.1 parts by weight of milk, 85 parts by weight of granulated sugar, 1 part by weight of citrus fiber, 2 parts by weight of seaweed powder, and 11.9 parts by weight of glutinous rice starch; and the fermentation bacteria are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus, with a total addition amount of 200 dcu / ton.

[0086] The preparation method is as follows:

[0087] After milk is transferred from the milk silo, it is heated to 20°C on a hot plate and directly pumped into the batching tank. Sugar, citrus fiber, seaweed powder, and glutinous rice starch are added. After the ingredients are added, the product is homogenized at a primary pressure of 110 bar and a secondary pressure of 70 bar. After homogenization, it is sterilized at 130°C for 5 seconds. The liquid is cooled to 40°C before the bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus are added. Fermentation occurs in a fermenter. When the pH reaches 4.3, the milk is demulsified and stirred at 35 rpm for 10 minutes. After stirring, the milk is rapidly cooled in the fermenter to 20°C, resulting in the fermented milk. The cooled fermented milk is then pasteurized at 95°C for 300 seconds. After cooling to 25°C, it is canned.

[0088] Example 6

[0089] This embodiment provides a room temperature yogurt, the formula of which is as follows:

[0090] 898.1 parts by weight of milk, 85 parts by weight of granulated sugar, 3 parts by weight of citrus fiber, 3 parts by weight of seaweed powder, and 10.9 parts by weight of glutinous rice starch; the fermentation bacteria are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus, with a total addition amount of 200 dcu / ton.

[0091] The preparation method is as follows:

[0092] After milk is transferred from the milk silo, it is heated to 20°C on a hot plate and directly pumped into the batching tank. Sugar, citrus fiber, seaweed powder, and glutinous rice starch are added. After the ingredients are added, the product is homogenized at a primary pressure of 110 bar and a secondary pressure of 70 bar. After homogenization, it is sterilized at 125°C for 5 seconds. The liquid is cooled to 40°C before the bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus are added to the fermentation tank. When the pH reaches 4.3, the milk is demulsified and stirred at 35 rpm for 10 minutes. After stirring, the milk is quickly cooled in the fermentation tank to 20°C, resulting in the fermented milk. The cooled fermented milk is then pasteurized at 95°C for 300 seconds. After cooling to 25°C, it is canned.

[0093] Example 7

[0094] This embodiment provides a room temperature yogurt, the formula of which is as follows:

[0095] 899 parts by weight of milk, 85 parts by weight of granulated sugar, 2 parts by weight of citrus fiber, 4 parts by weight of seaweed powder, and 10 parts by weight of glutinous rice starch; the fermentation bacteria are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus, with a total addition amount of 200 dcu / ton.

[0096] The preparation method is as follows:

[0097] After milk is blended from the milk silo, it is heated to 20°C on a hot plate and directly pumped into the batching tank. The ingredients are added in the following order: white sugar, citrus fiber, seaweed powder, and glutinous rice starch. After the ingredients are added, the product is homogenized at a primary pressure of 110 bar and a secondary pressure of 70 bar. After homogenization, it is sterilized at 130°C for 5 seconds. The liquid is cooled to 40°C before the bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus are added. Fermentation occurs in a fermenter. When the pH reaches 4.3, the milk is demulsified and stirred at 35 rpm for 10 minutes. After stirring, the milk is rapidly cooled in the fermenter to 20°C, yielding the fermented milk. The cooled fermented milk is then pasteurized at 95°C for 300 seconds. After cooling to 25°C, it is canned.

[0098] Comparative Example 1

[0099] This comparative example is the same as Example 4, except that, in step (2) of this comparative example, the feed liquid of step (1) is cooled to 40° C., and Lactobacillus bulgaricus and Streptococcus thermophilus are added as fermentation strains in an amount of 300 dcu / ton.

[0100] Comparative Examples 2-5

[0101] In Comparative Example 2, other ingredients and preparation methods are the same as those in Example 4, except that seaweed powder is not used in the formula of this comparative example.

[0102] In Comparative Example 3, other ingredients and preparation methods are the same as those in Example 4, except that citrus fiber is not used in this comparative example.

[0103] In Comparative Example 4, other ingredients and preparation methods are the same as those in Example 4, except that: this comparative example uses citrus fiber that has not been frozen and ground with liquid nitrogen and has a fineness of 220 mesh.

[0104] In Comparative Example 5, other ingredients and preparation methods are the same as those in Example 4, except that corn starch is used instead of glutinous rice starch in this comparative example.

[0105] Comparative Example 6

[0106] This comparative example provides a room temperature yogurt, the formula of which is the same as that of Example 5, and the preparation method adopts a common heating process, as follows:

[0107] (1) After the milk is adjusted from the milk silo, it is directly pumped into the hot plate (hot plate temperature) at a pressure of 15 bar to heat the milk to 60°C in a cycle. After the heating is completed, it is directly pumped into the mixing tank and the raw materials are added. During the addition of raw materials, the milk is not circulated and heated, which reduces the shear of the product stabilizer and improves the stability of the product.

[0108] The added raw materials are white sugar, citrus fiber, seaweed powder and glutinous rice starch in order. After the feeding is completed, the product is homogenized with a first-level homogenization pressure of 120 bar and a second-level pressure of 50 bar. After homogenization is completed, it is sterilized with a sterilization temperature of 130°C and a sterilization time of 5 seconds to obtain a mixed liquid.

[0109] (2) The mixed liquid was cooled to 40° C., and Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus were added to the fermenter for fermentation. When the pH value reached 4.3, the emulsion was broken and stirred at a stirring speed of 35 rpm for 10 minutes. After stirring, the mixture was quickly cooled in the fermenter to 20° C. to obtain cooled fermented milk.

[0110] (3) The cooled fermented milk is pasteurized at 95°C for 300 seconds and cooled to 25°C to obtain room temperature yogurt.

[0111] Comparative Example 7

[0112] This comparative example provides a room temperature yogurt, the formula of which is as follows:

[0113] 900.1 parts by weight of milk, 85 parts by weight of granulated sugar, 3 parts by weight of seaweed powder, 11.9 parts by weight of glutinous rice starch; and fermentation bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus, with a total addition amount of 200 dcu / ton. The preparation method is the same as in Example 5.

[0114] Comparative Example 8

[0115] This comparative example provides a room temperature yogurt, the formula of which is as follows:

[0116] 899 parts by weight of milk, 85 parts by weight of granulated sugar, 2 parts by weight of citrus fiber, 4 parts by weight of seaweed powder, and 10 parts by weight of corn starch; the fermentation bacteria Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus are added in a total amount of 200 dcu / ton. The preparation method is the same as in Example 7.

[0117] Experimental Example 1 Comparison of product viscosity of Examples 1-4 and Comparative Examples 1-5

[0118] In this experiment, the viscosity (unit: mPa.s) of the products of Examples 1-4 and Comparative Examples 1-5 was measured using a rheometer at 25°C using a CC27 probe and a ramp rate of 75 seconds, as shown in Table 1. The target viscosity range was 220-380.

[0119] Table 1 Viscosity of products of Examples 1-4 and Comparative Examples 1-5

[0120] Experimental Example 2 Comparison of product stability during the shelf life of Examples 1-4 and Comparative Examples 1-5

[0121] The products of Examples 1-4 and Comparative Examples 1-5 were placed at 38° C. for heat preservation observation. The stability results of the products during the shelf life are shown in Table 2.

[0122] Table 2 Stability results of the products of Examples 1-4 and Comparative Examples 1-5 during their shelf life

[0123] Experimental Example 3 Comparison of product preferences of Examples 1-4 and Comparative Examples 1-5

[0124] This experimental example conducted a preference test on the products of Examples 1-4 and Comparative Examples 1-5.

[0125] Twenty randomly selected panelists conducted a product flavor test (also known as a "taste test"). This flavor test used a scoring method: a numerical method that evaluates products or product characteristics. The average score is used to determine quality. Scoring was based on a 0-10 scale, with 0-2 considered poor, 3-5 considered fair, 6-8 considered good, and 9-10 considered excellent. Evaluation criteria included color, flavor, and mouthfeel. The flavor test results are shown in Table 3.

[0126] Table 3 Product preference rating results of Examples 1-4 and Comparative Examples 1-5

[0127] It can be seen from Tables 1-3 that compared with Example 4, after omitting or replacing the type of stabilizer (citrus fiber, seaweed powder, glutinous rice starch) in Comparative Examples 2, 3 and 5, although the re-viscosity defect basically did not occur during the shelf life of the ambient temperature yogurt, the initial viscosity and stability of the ambient temperature yogurt prepared in Comparative Examples 2, 3 and 5 did not meet the requirements.

[0128] For example, the product obtained in Comparative Example 2, which did not use seaweed powder, developed patterns within one month and began to precipitate water from the second month. Its stability during the shelf life was poor, which shows that seaweed powder is an indispensable stabilizer and the absence of seaweed powder will greatly affect the stability of the product during the shelf life.

[0129] The product obtained in Comparative Example 3, in which citrus fiber was not used, showed slight water precipitation starting from the second month. Its stability during the shelf life was poor, and the viscosity remained at a low level throughout the shelf life. This shows that citrus fiber is an important factor affecting viscosity and is also the main reason for the viscosity rebound during the shelf life. To solve the problem of viscosity rebound during the shelf life, in-depth research on citrus fiber is needed.

[0130] The product obtained in Comparative Example 5, which uses corn starch instead of glutinous rice starch, also showed slight water separation starting in the second month, and its stability during the shelf life was poor. This also shows that the product of the present invention requires the use of glutinous rice starch with higher viscosity, rather than corn starch with lower viscosity. Maintaining product viscosity is also a key factor in maintaining product stability. In other words, the product of the present invention must have a certain viscosity to maintain stability, while also avoiding the phenomenon of viscosity rebound during the shelf life.

[0131] Compared to Example 4, the initial viscosity and stability of the ambient temperature yogurt prepared in Comparative Example 1, after increasing the amount of starter, did not meet the requirements. This confirms that in a yogurt system using citrus fiber, seaweed powder, and glutinous rice starch as stabilizers, changing the amount of starter can seriously affect the fermentation and stability of ambient temperature yogurt.

[0132] Compared with Example 4, Comparative Example 4 provides ordinary citrus fiber with the same fineness of 220 mesh but not subjected to liquid nitrogen grinding (liquid nitrogen grinding products will not produce caking, thermal denaturation and other problems due to high temperature grinding). The results show that even if the fineness is the same, since the citrus fiber has not been pretreated, it will still cause the yogurt system to stick back after being used as a stabilizer, and due to the simplification of the preparation method, the 220 mesh citrus fiber that has not been treated with liquid nitrogen is used as a stabilizer together with seaweed powder and glutinous rice starch, and the stability effect is very limited. As shown in Table 1, the viscosity of Comparative Example 4 is 30%, 41%, 54% and 78% higher than that of Example 4 at one month, two months, three months, four months and five months, respectively, which shows that the viscosity of the comparative example increases month by month, and the rate of increase in viscosity increases month by month relative to Example 4; as shown in Table 2, the product prepared by Comparative Example 4 has patterns at two months and water separation at the third month; and as shown in Table 3, its mouthfeel is significantly lower than that of Example 4.

[0133] Experimental Example 4

[0134] In this experimental example, the viscosity (unit: mPa.s) of the products of Examples 5-7 and Comparative Examples 6-8 was measured using a rheometer at 25°C using a CC27 probe and a ramp rate of 75 seconds. The results are shown in Table 4.

[0135] Table 4

[0136] Experimental Example 5

[0137] The product formulations of Examples 5-7 and Comparative Examples 6-8 were sterilized for the first time (ultra-high temperature instantaneous sterilization) and the tubes were removed to observe whether there was any sticking of the tubes. The results are shown in Table 5.

[0138] Table 5

[0139] Experimental Example 6

[0140] The products of Examples 5-7 and Comparative Examples 6-8 were placed at 38°C for heat preservation observation. The stability results of the products during the shelf life are shown in Table 6.

[0141] Table 6

[0142] Experimental Example 7

[0143] This experimental example conducted a preference test on the products of Examples 5-7 and Comparative Examples 6-8.

[0144] Twenty randomly selected tasters conducted a flavor test (also known as a "taste test"). This flavor test used a scoring method: a numerical method that evaluates products or product characteristics. The average score is used to determine quality. Scoring was based on a 0-10 scale, with 0-2 considered poor, 3-5 considered fair, 6-8 considered good, and 9-10 considered excellent. Evaluation criteria included color, flavor, and mouthfeel. The flavor test results are shown in Table 7.

[0145] Table 7

[0146] As shown in Tables 4-7, only appropriate raw materials and processes can ensure product stability and taste. Improvements in the product's chemical processing can significantly reduce tube sticking during production and significantly reduce the amount of starch added. Starch from different sources can affect product viscosity, stability, and taste.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A zero-added room-temperature yogurt, characterized in that, The zero-added room temperature yogurt uses a mucilage-producing bacterium as the fermentation strain, and the addition amount of the fermentation strain is 200 dcu / ton; The stabilizer of the zero-added room temperature yogurt includes: citrus fiber, seaweed powder and glutinous rice starch. The citrus fiber is citrus fiber after cryogenic grinding. The cryogenic grinding conditions are: putting the roughly ground citrus fiber into liquid nitrogen for soaking to form a layer of ice on its surface and then grinding until the fineness reaches 150-220 mesh. Optionally, the mucilage-producing bacterium is Lactobacillus bulgaricus and Streptococcus thermophilus.

2. The zero-added room-temperature yogurt according to claim 1, wherein The raw materials of the zero-added room temperature yogurt are composed of milk, citrus fiber after cryogenic grinding, seaweed powder, glutinous rice starch, granulated sugar and mucilage-producing bacterium.

3. The zero-added room-temperature yogurt according to claim 2, wherein In the zero-added room temperature yogurt, by mass, the ratio of citrus fiber after cryogenic grinding, seaweed powder to glutinous rice starch is (1-4):(2-6):(14-20).

4. The zero-added room-temperature yogurt according to claim 3, characterized in that, In the zero-added room temperature yogurt, by mass, the ratio of citrus fiber after cryogenic grinding, seaweed powder, glutinous rice starch is 1:2:14 or 4:6:

20.

5. The zero-added room temperature yogurt according to claim 4, characterized in that, In the zero-added room temperature yogurt, there are 871-903 parts by weight of milk, 1-4 parts by weight of citrus fiber after cryogenic grinding, 2-6 parts by weight of seaweed powder, 12-20 parts by weight of glutinous rice starch and 70-90 parts by weight of granulated sugar.

6. The preparation method of the zero-added room-temperature yogurt according to any one of claims 1-5, characterized in that, Including: Adding granulated sugar, citrus fiber after cryogenic grinding, seaweed powder, glutinous rice starch to the pretreated milk in sequence to obtain a mixed material liquid, and using the mucilage-producing bacterium to ferment the mixed material liquid to obtain the zero-added room temperature yogurt. Optionally, the mucilage-producing bacterium is Lactobacillus bulgaricus and Streptococcus thermophilus. Optionally, the pretreatment is to heat the milk to 55-60 °C. Optionally, after adjusting the milk from the milk silo, use pressure to pump the milk into the hot plate to make the milk circulate and heat up to 55-60 °C. Optionally, the pressure is 10-15 bar.

7. The preparation method of the zero-added room-temperature yogurt according to claim 6, characterized in that, Including: (1) Heating the milk to 55-60 °C, and sequentially adding granulated sugar, citrus fiber after cryogenic grinding, seaweed powder and glutinous rice starch to the heated milk for homogenization and sterilization to obtain a mixed material liquid; (2) Cooling the mixed material liquid in step (1) to 40-42 °C, adding the mucilage-producing bacterium for fermentation. When the pH value reaches 4-4.3, demulsify, stir and cool to obtain fermented milk. Optionally, cool to 20-25 °C; (3) Performing pasteurization and cooling on the fermented milk obtained in step (2) to obtain the zero-added room temperature yogurt. Optionally, cool to 20-25 °C.

8. The preparation method of the zero-added room-temperature yogurt according to claim 7, characterized in that, The conditions of the homogenization in step (1) are: the first-stage pressure is 110-150 bar, and the second-stage pressure is 50-80 bar; the conditions of the sterilization in step (1) are: 130-135 °C, 3-5 s.

9. The preparation method of the zero-added room-temperature yogurt according to claim 7, characterized in that, The rotation speed of the demulsifying and stirring in step (2) is 35-40 revolutions per minute, and the stirring time is 10-12 minutes.

10. The preparation method of the zero-added room-temperature yogurt according to claim 7, characterized in that, The temperature of the pasteurization in step (3) is 95 °C, and the time is 200-300 s.

11. A preparation method of room-temperature yogurt, characterized in that, Including: Add white granulated sugar, citrus fiber, seaweed powder and glutinous rice starch to milk at 18-25°C for material melting. After material melting, homogenize and sterilize to obtain a mixed material liquid. Inoculate and ferment the mixed material liquid to obtain fermented milk, and obtain the room-temperature yogurt after pasteurization. Optionally, the fermentation strains are Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus subsp. salivarius; The citrus fiber is citrus fiber after cryogenic grinding. The cryogenic grinding conditions are: put the roughly ground citrus fiber into liquid nitrogen for soaking to form a layer of ice on its surface, and then grind until the fineness reaches 150-220 mesh. Optionally, the mass ratio of the cryogenically ground citrus fiber, seaweed powder and glutinous rice starch is (1-4):(2-6):(10-20).

12. The preparation method of the room-temperature yogurt according to claim 11, wherein By weight, except for the fermentation strains, the raw materials of the room-temperature yogurt are: 880-917 parts of milk, 1-4 parts of cryogenically ground citrus fiber, 2-6 parts of seaweed powder, 10-20 parts of glutinous rice starch and 70-90 parts of white granulated sugar.

13. The preparation method of the room-temperature yogurt according to claim 11 or 12, characterized in that, The preparation method includes: (1) Heat the milk to 18-25°C, add white granulated sugar, citrus fiber, seaweed powder and glutinous rice starch for homogenization and sterilization to obtain a mixed material liquid; (2) After cooling the mixed material liquid to 40-42°C, add Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus subsp. salivarius for fermentation. When the pH value reaches 4.3, break the emulsion and stir, then cool to obtain fermented milk; (3) Pasteurize the cooled fermented milk and then cool to obtain the room-temperature yogurt.

14. The preparation method of the room-temperature yogurt according to claim 13, wherein, In step (1), the conditions for homogenization are: the first-stage pressure is 110-150 bar, and the second-stage pressure is 50-80 bar; the conditions for sterilization are: 125-135°C, 3-5 s.

15. The preparation method of the room-temperature yogurt according to claim 13, wherein, In step (2), the rotation speed for breaking the emulsion and stirring is 35-40 revolutions per minute, and the stirring time is 10-12 minutes.

16. The preparation method of the room-temperature yogurt according to claim 13, characterized in that, In step (3), the conditions for pasteurization are: 95°C, 200-300 s, optionally 300 s.

17. A room-temperature yogurt, characterized in that, Prepared by the preparation method according to any one of claims 11-16, the raw material composition of the room-temperature yogurt is: 888.1-917 parts of milk, 1-4 parts of cryogenically ground citrus fiber, 2-6 parts of seaweed powder, 10-11.9 parts of glutinous rice starch and 70-90 parts of white granulated sugar, and the fermentation strains Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus subsp. salivarius. Optionally, the room-temperature yogurt does not separate water when placed at 38°C for 6 months.

Images